Hello,
If you purchase individual product, for example, Fences 3, now. You will get a license key for it and this key will be valid for all version of Fences 3.xx forever. You will only need to purchase a new license key if you wish to use Fences V4 in the future.

Thanks
Basj,
Stardock Community Assistant.

Hello,

If you already purchase Fences V3 and already have the license key. You could enter the before the trial expired. Open up Fences Configuration Windows-> Click About-> And there should be something like screenshot below.

Basj,
Stardock Community Assistant.